Hydroelectricity is electricity produced from hydropower. Hydropower is the most environment friendly and consistent resource, proficient of meeting peak load electricity requirements with large water storage technology. Unlike the thermal power that takes long time to start once it is shut down,the hydroelectricity generation can be stared at once in order to meet the unexpected demand of scarcities or of intermittent power sources.


 There are some adverse effects of construction of dam on the environment and ecology of the are.   It all depends on the size of the reservoir. The size of the reservoir formed by a hydroelectric dam can vary extensively, depending largely on the height of the hydroelectric Dams and the topography of the land. Hydroelectric plants in flat areas tend to involve much more land than those in hilly areas. Flooding land for a hydroelectric reservoir has an adverse environmental effect.It destroys forest, wildlife habitat, agricultural land, and the scenic landscape of the area. 

Global warming emissions are produced during the installation and dismantling of hydroelectric power plants. Such emissions vary significantly depending on the size of the reservoir and the nature of the land that is flooded by the reservoir. 

Wildlife impacts: Dammed reservoirs are used for multiple tenacities, such as agricultural irrigation, flood control, and recreation, so not all wildlife effects associated with dams can be directly attributed to hydroelectric power. Hydroelectric services can still have a major effect on aquatic ecosystems.

A after the commissioning of the dam,then there is very little adverse effect of the dam. Compared to this the benefits are great.